1. Field of the Invention
The present invention relates to a camera for supporting a roll film having perforations along its upper and lower edges and a roll film not having the perforations. More particularly, this invention is concerned with a camera for employing a film cartridge of a size 135 specified in the Japanese Industrial Standard (JIS) and switching photographic screen sizes depending on the presence or absence of perforations on a roll film.
2. Description of the Related Art
A camera capable of switching photographic screen sizes for a roll film has been disclosed in Japanese Patent Laid-Open No. 36-14234 in the past. This camera changes photographic screen masking plates and finder window sizes simultaneously. Using the same camera, photographic screen sizes are changed externally according to the purposes of photography, then photographs are taken. The spacing of photographic screens is held constant, and a photographic screen size is displayed on the finder window.
Japanese Patent Laid-Open No. 58-142324 has disclosed a large-sized camera that is designed for a Brownie film and still supports a JIS 135-size film. In the camera, a film advancing drive is incorporated. The film advancing drive is operated using an advancing lever formed on a camera body, so that a Brownie film take-up and a film take-up for a JIS 135-size film cartridge can be switched freely. In each of the Brownie film take-up and JIS 135-size film cartridge take-up, a film advancing mechanism interlocked with the film advancing drive is incorporated.
Japanese Utility Model Publication No. 48-35775, which has no relation to a camera capable of switching photographic screen sizes, has described that films are exposed in different screen sizes using cartridges of the same kind, then the screen sizes adopted for the films in the cartridges are identified by looking at the appearances of the cartridges.
In conventional cameras capable of switching photographic screen sizes, photographic screen sizes are switched manually and the switching mechanisms are complex. The Japanese Patent Laid-Open No. 36-14234 has disclosed a photographic screen switching means. Herein, when a JIS 135-size film cartridge is employed, photographic screens are changed from a standard size of 24 mm by 36 mm to a half size of 24 mm by 18 mm; that is, only the length in the film feeding direction can be changed. At this time, the film length in the direction orthogonal to the feeding direction cannot be changed. Therefore, photographic screens can be shrunk to the half size and exposed easily. It is, however, hard to provide photographic screens larger than the standard size, because a film can be enlarged only in the feeding direction.
The art disclosed in the Japanese Patent Laid-Open No. 58-142324 is restricted to large-sized cameras using a Brownie film or other large-sized film but cannot apply to cameras capable of loading only a JIS 135-size film cartridge. To change the sizes of photographic screens, a film of a different size must be loaded. When only, for example, a JIS 135-size film cartridge is in use, photographic screens cannot be altered.
A film loaded in the JIS 135-size film cartridge is perforated on its sides as stipulated in JIS Standard K7519-1982 "135-size Film Cartridge" or ISO Standard 1007 "Photography-135-size Film and Magazine Specification." Due to the perforations, only 25.4 mm is ensured as an effective photographic width for a film width of 35 mm. Therefore, a standard photographic screen size is 24 mm by 36 mm as stipulated in JIS Standard B7115. The effective use rate in the direction orthogonal to the film feeding direction is 0.69 or a quotient of 25 by 35, which is smaller than 70%. Unlike photographs taken at an improved effective use rate at which the photographic screen size is increased fully within the film width of 35 mm, photographs taken in the standard photographic screen size must be enlarged greatly during printing. Therefore, the quality of a print image deteriorates.
The perforations are designed for intermittent feeding of cinefilm, and not always necessary for normal still cameras. Consequently, when perforation is abolished, larger photographic screens are provided. This results in a smaller enlargement ratio during printing. High-quality print images ensue.